I would think low ranked online is probably still alive due to the F2P nature of the game, just expect to fight a LOT of the few free characters. Haven't played in a while but I got up to a low C I think and had no trouble finding games, though it's been at least a couple of months. Gameplay itself is fine and they fixed the initially terrible costume unlock system. On Xbox you can individually buy costumes for reasonable-ish prices, or just get the few characters they've added and not support the cosmetics. Last I saw on PS4 they were coming up with some kind of microtransaction currency to let you buy the costumes that are otherwise only in expensive bundles.
Really though, around these prices you're probably better off getting either Tekken 7 or Soul Calibur VI during the holiday sales as those are both confirmed to have major support going on with each getting a new season. DOA6 has a small playerbases on all platforms, though I imagine you'll still keep getting more characters as costumes are obviously where they make their money, I'd guess the few missing older characters and some of the new women from the Xtreme game that's active in Japan currently. Even if you're only buying for the tiddy I'd say Soul Calibur probably fills that niche better since you can create costumes.
Main reason to pick up DOA6 at this point is if you're all in on DOA's (or Virtua Fighter's) specific gameplay mechanics, as the three remaining 3D fighters all feel pretty different.
